Evaluation of the damage and pollinator role of three thrips strains on cowpea in Burkina Faso.

Abstract

Thrips are insect pests associated with many wild and cultivated plants, including
cowpeas. This study was initiated to assess the damage and pollinating role of thrips
associated with cowpeas in cultivation. Two cowpea varieties were sown in pots
arranged in Fisher blocks randomized in four and three replications respectively for
the improved KN1 and wild E210 varieties. The plants were treated with the
insecticide K-optimal (at a dose of 2 ml/L) at 21 days after sowing, then covered with
mosquito netting. At flower bud formation, 24 and 21 plants respectively for varieties
KN1 and E210 per agro-ecological zone were infested with thrips from three
localities. The numbers of flowers formed, fallen and pods formed were the
parameters measured. The increase in the number of thrips at the time of infestation
led to an increase in the number of fallen flowers and a decrease in the number of pods
formed on both varieties. This trend became more pronounced with the more
aggressive sahelian strain. Infestation levels of 60 thrips or more per plant caused
significant flower drop on the KN1 variety. On the E210 variety, no pods were
observed on control plants, while thrips caused maximum pod formation at 30 thrips
per plant. This study revealed thrips as pests for the KN1 variety and possible
pollinators for the E210 variety.